US3744204A

US3744204A - Unit platform

Info

Publication number: US3744204A
Application number: US00246673A
Authority: US
Inventors: D Eshler
Original assignee: Gypsum Co
Current assignee: United States Gypsum Co; Gypsum Co
Priority date: 1972-04-24
Filing date: 1972-04-24
Publication date: 1973-07-10
Anticipated expiration: 1990-07-10

Abstract

A unit platform comprising a grating supported at three sides thereof by a portion of a frame underlying the grating, the supporting portions being outwardly lanced projections giving under-support to the grating while remaining integrally attached at their ends to the frame.

Description

Umted States Patent 1191 1111 3,744,204 Eshler Jul 10 1973 [54] UNIT PLATFORM 1,471,569 10/1923 Pattison 52/666 1,553,474 9/1925 Price 52/666 [751 Invent Eshle" warren Ohm 1,734,471 11/1929 Brown 52/666 [73] Assignee: United States Gypsum Company,

Chlcago, Primary Examiner-John E. Murtagh [22] Filed; Apt 2 7 AttorneyStanton T. Hadley, Dana M. Schmidt eta. [21] Appl. No.: 246,673

[57] ABSTRACT (SI. 52/67I;(,M5c2/2 A unit platform comprising a grating pp n at three [58] Fie'ld 177 671 sides thereof by a portion of a frame underlying the 52,670 666 6 3 6 grating, the supporting portions being outwardly lanced projections giving under-support to the grating while [56] References Cited remaining integrally attached at their ends to the f UNITED STATES PATENTS tame 1,304,056 8 Claims, 7 Drawing Figures 5/1919 lrving 182/228 UNIT PLATFORM BACKGROUND OF THE INVENTION A great variety of grating has been used in the past to construct platforms such as catwalks, stair treads, factory flooring, and other supports wherein the platform must be both porous, and provided with a non-slip tread. Examples of one type are shown in U.S. Pat. Nos. 2,828,792 and 2,828,843. Still another type utilizes expanded metal sheet in contrast with the disclosed structure of the aforementioned patents. Such a type is illustrated in U.S.,Pat. No. 3,496,688. The difficulty with expanded metal sheet is that its expanded nature renders impractical the construction of the frame of the platform, as well as the tread, from the expanded sheet. Accordingly, it has been conventional in the construction of unit platforms such as stair treads as shown in U.S. Pat. No. 3,496,688, to provide a separate bar shaped as a C to provide a frame to which the grating is welded. Generally, the welding is accomplished by two different techniques. At the side legs of the C frame, portions of the grating overlie the legs and are arc-welded thereto. At the intermediate portion of the C-shaped bar which defines the front of the unit platform, the expanded nature of the grating renders unsuitable any attempt to overlie the grating on the bar and then weld it thereto. That is, a straight edge is needed, which the leading edge of the expanded sheet can not provide. Accordingly, the leading edge of the grating is conventionally located just behind the intermediate portion of the bar, an tack welded thereto. One difficulty of such a construction is that the sole vertical support of the leading edge is the tack weld. Another difficulty is that tack weldig is more costly and time consuming than other forms of welding.

Still other unit platforms such as stair treads have been provided in the past by riveting various parts thereof together. One example is shown in U.S. Pat. No. 1,304,056, wherein cantilevered punched-out tabs are provided to suppoart the grating at the side legs of the frame. However, the connection of the grating to the frame is accomplished by rivets, rather than at the legs. This is particularly true of the grating connection at the front of the stair tread, so that the rivet rather than the frame provides the vertical support.

SUMMARY OF THE INVENTION The invention relates to a unit platform such as a stair tread, wherein a novel mounting of the grating is provided. More specifically, the invention concerns a unit platform comprising a frame and an expanded metal grating welded thereto, the platform being characterized in that a portion of the frame underlies the grating along all of the sides of the frame, whereby the frame, and not the welds, provides the vertical support of the grating. Preferably, the support is provided by support members projecting from the frame, each of which is anchored at two spaced points, preferably their ends, to the frame.

Accordingly, it is an object of the invention to provide a unit platform which has an improved mounting of the grating to the frame, so that at all connections of the grating thereto, a portion of the frame underlies the grating and provides the vertical support therefor.

It is a related object of the invention to provide such a unit platform in a more economical manner by rapid manufacturing techniques.

Other objects and advantages will become apaprent upon reference to the following drawings and detailed discussion.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a stair tread constructed in accordance with the invention;

FIG. 2 is a side elevational view of the stair tread of FIG. 1;

FIG. 3 is a bottom view of the stair tread of FIG. 1;

FIG. 4 is a fragmentary sectional view taken generally along the line IVIV of FIG. 3;

FIG. 5 is a sectional view taken generally along the line V-V of FIG. 3;

FIG. 6 is a fragmentary sectional view taken generally along the line VI-VI of FIG. 3; and

FIG. 7 is a fragmentary elevational view of one use of the stair tread shown in the previous figures.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The disclosure concerns a unit platform, such as a stair tread, wherein the grating of the platform is given more positive support than has been conventional. For purposes of illustration, the invention will be shown as a stair tread. However, it is broader than this in scope, applying to any platform which lends itself to unit construction. One example of another structure is a landing of a size permitting such unit construciton.

Words of orientation such as horizontally and vertically are used herein not in any absolute sense, but only to describe the relative orientations of the product of the invention when finally assembled.

Turning now to the drawings, a stair tread 10 comprises a conventional grating l2.connected to a threesided C-shaped frame 14 having

openings

16 and 18 for attachment of the stair tread into a ladder or staircase 60. The frame 14 specifically comprises a bar having an intermediate portion 20 and

legs

22 and 24 extending generally perpendicular therefrom. The frame thus defines a generally rectangular space the fourth side of which is open. The grating 12 covers or spans this space, and is a metal sheet conventionally expanded to produce a generally planar grating having tilted diamond-shaped opening 26 and sheared ends 27. FIG. 1 illustrates a nosing angle 30 tack-welded to the intermediate portion 20, which angle has been divided for purposes of illustration only into two portions. Portion 32 is a regular nosing angle provided with raised dimples 33 angled with respect to each other. Portion 34 is an abrasive nosing angle having grit 36 adhered to the surface. Either, but usually not both, nosing angle may be used if additional non-slip safety is required. Or alternatively, the nosing angle canbe omitted entirely, leaving the intermediate portion 20 of the bar. Still another alternative is to notch or serrate, not shown, that portion 20 along the upper edge, thereby roughening the edge for non-slip purposes.

In accordance with one aspect of the invention, the grating is supported on all three frame sides thereof by a portion of the frame underlying the grating. More specifically, support members 40 comprise arcuate shaped projections lanced outwardly into the space enclosed by frame 14 and covered by the grating, the supporting members being anchored at their two

opposite ends

42 and 44 to the frame 14 (FIGS. 4-6). For maximum strength, the supporting members preferably are lanced outwardly only at center portion 46, leaving the

ends

42 and 44 remaining integral with the frame. The members 40 are spaced along the entire length of the bar and are lanced out to extend generally within a plane which is substantially parallel to the overall plane of the grating. Specifically, the support members 40 are formed in the legs 22 an 24, as well as the intermediate portion 20. Preferably, enough members 40 are formed in the intermediate portion 20 to support the leading edge of every diamond-shape in row A (FIG. 3). Thus the leading edge of the grating, identified in the drawings as 260, is supported at each point where it projects into the vicinity of portion 20 of the frame, by a member 40.

As best seen in FIG. 3, it is the support members of the frame which give the vertical support to the rating. grating. permanently secure the grating on members .40, the sheared ends 27 of the grating and the leading portions 260 of row A of the diamonds 26 are pressure welded (FIGS. 4-6) approximately to the center portion 46 of the support members. Pressure welding has the advantage of speed, compared to arc welding and tack welding. It will be readily apparent that the welds serve only to keep the grating and frame from separating horizontally, vertical support being provided by the support members 40 only.

Turning now to FIG. 7, one end use of the platform described above as a stair tread is in a ladder 60. Such a ladder comprises two parallel side members 62 inclined from the vertical, and horizontally positioned stair treads l spaced along the side members and attached, such as by bolts, thereto. The treads illustrated have been provided with an abrasive nosing 34.

A stair tread constructed as described above with a length of 30 inches, a grating weight of 4 pounds/sq.ft., and a frame thickness of three-sixteenth inches, was found to support a load of 7 l0 pounds as a safe concentrated load, when tested in accordance with 1968 A181, Section 6. It will be readily determined that the above length is in no way a limitation, as much longer stair treads may be required for use such as on off-highway vehicles.

Although the invention has been described in connection with certain preferred embodiments, it will be recognized that it is not limited thereto. Rather, it is intended that it include all alternate arrangements, equivalents, and embodiments as may be included within the scope of the following claims.

What is claimed is:

1. In a unit platform including an external frame member and a grating connected to the frame member and spanning the space defined by the frame member; the improvement comprising support members projecting into said space from said frame, each of said support members being anchored at two separate points to the frame, said grating being connected to said support members only.

2. The improved platform as defined in claim 1, wherein said grating has an overall planar orientation and said support members are generally arcuate in shape, lying generally in a first plane that is substantially parallel to the plane of the grating.

3. The improved platform as defined in claim 2, wherein said support members are projections lanced along the frame member at spaced intervals along the complete length of the member and lying in said first plane, the projections retaining a connection to said frame member at their opposite ends.

4. The improved platform as defined in claim 1, wherein said frame member is a generally C-shaped bar and wherein said grating is connected to said support member by pressure welds.

5. The improved platform as defined in claim 1, wherein said grating is an expanded metal sheet.

6. In a unit platform including a generally C-shaped bar defining a space between the open legs thereof, and an expanded metal grating welded to said bar and extending out across said space; the improvement comprising arcuately-shaped support members integral with said bar and projecting therefrom into said space a distance sufficient to underlie the grating, and thence back to the bar, said members each being thus connected to the bar at two opposite ends, said grating being welded to said bar at said members only, by pressure welds.

7. The improved platform as defined in claim 6, wherein the intermediate portion of said bar defining the back of the C-shape is provided with at least one of said support members, said grating being pressure welded thereto, whereby the vertical support of the grating in the vicinity of said intermediate bar portion is provided by the bar.

8. A unit platform comprising a three-sided frame open at a fourth side, and an expanded metal grating welded thereto, the platform being characterized in that a portion of the frame underlies the grating at all of said three sides, whereby the frame, and not the welds, provides the vertical support for the grating.